darkhog, I'll make them for you. I'm sure it's not that hard. Just depending on my schedule, it may or may not get done in December :-)
Edit: I've had a bit of a look today. Indeed, it's not that difficult. Just trying to wrap my head around what I *think* are the animation sequences. It's possible that each type of thing has a different notation? But I'll make a Github repository with my work and you (or anyone else) can start from there. I'll probably make an "invisible" graphics set which just uses official TXT files, but uses transparent tilesets. This should mean that everything will work, but that you won't be able to see anything. I'll also try to document what the TXT files mean and how they relate to the actual tiles if I can figure it out.
(Second edit: doesn't need answering) Toady, please tell me if the TXT files in the graphics directories (for example data/vanilla/vanilla_buildings_graphics/graphics_workshops.txt) are *not* public domain. I assume they are because I can't imagine being able to make a graphics set without essentially basing it on those.
Second Edit: I notice a clear statement in the readme putting those files in the public domain, so I guess it's good to go. Going to remove the limegreen since I don't think my query needs answering.
Third (and last) Edit:
https://github.com/mikekchar/df-invisible-gs Currently no pngs yet, but hopefully I'll get to it relatively soon. However, these are all the raw txt files.